1. Field of the Invention
This invention relates generally to a computer mouse that protects the user from developing Carpal Tunnel Syndrome or from aggravating an existing such condition and, more specifically, to a computer mouse having a curved member on its upper surface that can be repositioned to adapt to different shapes and sizes of hands.
2. Prior Art
According to the third edition of the American Medical Association Family Medical Guide, nerves run through confined spaces at certain points in the body where they can become severely pinched if surrounding tissues become swollen. A major nerve particularly subject to this kind of damage is one that carries signals between the brain and hand. As it travels through the wrist, this nerve passes through a tunnel formed by the wrist bones (known as the carpals) and a tough membrane on the underside of the wrist that binds the bones together. The tunnel is rigid, so that if tissues within it swell for some reason, they press on and pinch the nerve. This leads to a condition called Carpal Tunnel Syndrome. American Medical Association Family Medical Guide, 3rd Edition (Random House 1994), page 300.
The symptoms of Carpal Tunnel Syndrome are a tingling, intermittent numbness of part of the hand often accompanied by pains that shoot up the forearm from the wrist. If severe, permanent numbness and limited movement of the thumb and possibly the fingers can result. Common treatments for this unfortunate condition include wearing a splint about the wrist, cortisone injections and even operations to open and enlarge the tunnel.
People who do extensive work on computer keyboards and computer mouses are among those who are most at risk of developing Carpal Tunnel Syndrome. This is because strenuous or repeated use of the wrist, and particularly repeated actions that include bending of the wrist, cause Carpal Tunnel Syndrome. The typical computer keyboard and computer mouse require the operator to significantly bend his or her wrist, and repeated use of the keyboard or mouse over an extended period of time can cause Carpal Tunnel Syndrome.
Several attempts have been made to design a computer mouse to reduce hand and wrist muscle fatigue. However, these designs generally do little to prevent bending of the wrist, cannot be adjusted to meet the needs of a particular user and would be expensive to acquire. U.S. Pat. No. 4,862,165 to Gart discloses an ergonomically-shaped hand controller that is molded to have various curves on the surface for supporting the hand during use. However, the device is not directed to preventing the wrist from bending during use. Also, the locations and sizes of the curves cannot be adjusted to fit a particular shape or size of hand. Consequently, the premolded curves of Gart may not properly support the hand of a given user. Furthermore, a user that already owns a computer mouse would need to specially purchase the Gart mouse in order to take advantage of the Gart invention. Consequently, a mouse of this type is not likely to meet the needs of many users, and would also be expensive for most users to acquire.
U.S. Pat. No. 4,913,573 to Retter discloses a unique computer keyboard having a raised central portion designed to ergonomically support and steady the hand of the operator. While the Retter patent does not disclose a computer mouse per se, even if a mouse were to be constructed having the raised central curve of Retter, the position of the curve could not be adjusted to adapt to the shape and size of various users' hands. Additionally, as with the Gart device, a user would need to replace their existing mouse with a new mouse.
U.S. Pat. No. 5,157,381 to Cheng discloses a computer mouse having a curved upper surface to support the base of the fingers and the palm of the hand. As with the Gart and Retter devices, the Cheng upper surface does not adapt to differently shaped hands, and a user would need to replace his or her existing mouse with a Cheng mouse. The mouse also does not prevent the repeated bending of the wrist that can cause Carpal Tunnel Syndrome.
Accordingly, there is a long felt need for a system that a user may purchase and install on his or her existing computer mouse to prevent bending of the wrist and to better support the hand during use of the mouse. Additionally, there is a need to provide existing computer mice with a curved upper surface that can be adjusted to adapt to the differing shapes and sizes of different users' hands.